The present invention relates generally to measuring the blending efficiency of an adhesive resin with wood flakes and more particularly, to a system for measuring adhesive resin distribution on the wood flakes.
Many wood-based composite materials are in use for construction of homes, furniture and various products. These composite materials are generally available in sheet or panel form. Conventional composites are generally produced by adding a heat-curing adhesive resin composition to wood fibers and pressing the wood fibers together to form the sheet or panel.
Wood fiber is processed similarly for particle and fiber materials to prepare the end product of wood-based composite material. The wood fiber is flaked or chipped from wood, typically logs. Wood may be reduced to particles or strands. Wood chips may be steamed to soften the wood and reduce its composition to fibers. Fiberboard, Oriented Strandboard (OSB), and waferboard are generally prepared by drying the wood fibers or flakes/chips, adding an adhesive resin, and placing on a surface as a mat. The mat is pressed, generally by a platen-type press using heat and pressure to cure the adhesive resin. The wood particles, strands or fibers become bonded by the adhesive resin, and the bonded wood-based composite may then be cut to a desired size.
Waferboard was originally made from aspen. As the wood-based composite industry grew, Oriented Strandboard (OSB), a wood-based composite that included other hardwoods became the main wood-composite material. OSB is generally prepared from thin hardwood or pine strands that are aligned in a selected direction, then bonded together with waterproof adhesive resin using heat and pressure. The aligned or xe2x80x9corientedxe2x80x9d strands provide better strength than the original products of waferboard. The OSB may be used, for example, for walls, roofs, and floor covering material in commercial building and home construction.
Often, wood flakes are tumbled in a blender with adhesive resin, allowing the adhesive resin to coat the wood flakes so that, upon applying pressure and heat to a mat of the resin-coated flakes, the adhesive resin will bond the flakes, forming the desired wood-based composite. Typically, in order to assess the sufficiency of the blending, samples of the wood flakes have been taken from the blended mixture, and then the samples were examined using high magnification and/or special lighting and special cameras. While these methods were better than a simple visual analysis, these types of systems have generally required special care and have been very expensive to repair and use at multiple locations.
Current systems for determining the sufficiency of the adhesive resin coverage of the wood flakes employ the use of a microscope and a video camera or video camera and magnifier. These systems are expensive and take an hour and a half to two hours to complete measurement of a sample. For example, an RDM system from Eagle Analytical, Blackburg, Va. costs about $40,000. A system from Forintek, Ottawa, Ontario, Canada, costs approximately $25,000.
Thus, there remains a strong need for a method and system for providing inexpensive and efficient measurement of the sufficiency of the adhesive resin application to the wood substrate (e.g., how much adhesive resin is distributed onto the wood flakes) in order to facilitate the effective operation of a wood-based composite bonding process and to provide a more uniform wood-based bonded composite product.
The present invention provides a method for determining adhesive resin distribution/percentage of area covered on wood flakes that are to be formed into a wood-based composite. A predetermined amount of adhesive resin is generally sprayed onto a selected amount of wood flakes being tumbled in a blender prior to heat compression of the sprayed/blended wood chips into a wood-based composite. The method includes, after tumbling the sprayed/blended wood flakes in the blender, removing a sample of sprayed/blended wood flakes provided by the blender and placing the sprayed/blended wood flakes on a scanning bed, scanning the sprayed/blended wood flakes with a scanner having at least 1200 dpi (dots per inch) resolution with 1800 dpi interpolation to provide image data, using image analysis software with resin analysis macros that are installed on a computer to filter the image data to provide a high contrast image that shows each adhesive resin spot differentiated from uncoated wood flake on which the adhesive resin spot is situated, and measuring and analyzing the high contrast image to provide an output showing at least a percent coverage of the sprayed/blended wood flake by the adhesive resin.
The method may further include, after removing the sample of sprayed wood flakes, heating the sprayed/blended wood flakes until spots of adhesive resin are substantially differentiable from the portion of the wood flakes not covered by the adhesive resin. For example, the sample of wood flakes removed from the blender may be heated at 250xc2x0 F. for a predetermined time such as 15-45 minutes before scanning. Measuring and analyzing the high contrast image generally includes: determining an area of the adhesive resin spot/spots, determining an area of the wood flake on which the spot/spots are situated, determining a percent coverage of the area of the wood flake by the spot/spots, and determining an average percent coverage area of a preselected number of wood flakes by the adhesive resin spots.
The present invention also provides a system for determining adhesive resin distribution on blended wood flakes for wood-based composite production. The system includes a flatbed scanner and image analysis software with resin analysis macros that are installed on a computer. The flatbed scanner generally has at least 1200 dpi resolution with 1800 dpi interpolation and is arranged to receive a sample of the blended wood flakes, typically obtained from the output of a blender. The flatbed scanner scans the blended wood flakes to provide image data to image analysis software with resin analysis macros installed on a computer. The image analysis software with resin analysis macros receives the image data from the flatbed scanner and filters the image data to provide a high contrast image that shows each adhesive resin spot differentiated from the wood flake not having a resin coating on which the adhesive resin spot is situated, measures an area of each adhesive resin spot and the area of the uncovered wood flake on which the adhesive resin spot is located and analyzes the image data to provide an output showing at least a percent coverage of the wood flake by the adhesive resin. Where desired, the sample of sprayed wood flakes obtained from the blender may be heated, for example at 250xc2x0 F. for a predetermined time, until spots of adhesive resin are substantially differentiable from the uncovered region of the wood flakes. Typically, the sprayed/blended wood flakes may be heated for 15-45 minutes. Generally, the output may be displayed on a computer monitor and/or printed.
The method may be used for determining adhesive resin distribution on wood samples pulled from a wood-based veneer composite that has been water-soaked for a predetermined amount of time, in order to examine wood failure/glue failure to provide a grade for the wood-based veneer composite. The method includes the steps of: heating the wood flakes pulled from the wood-based veneer composite for one of: a predetermined time and until the wood flakes are substantially dry; placing said wood flakes on a scanning bed; scanning said wood flakes using at least 1200 dpi resolution with 1800 dpi interpolation to provide image data; using image analysis software with resin analysis macros installed on a computer wherein the image data of each wood sample is filtered to provide a high contrast image that shows adhesive resin differentiated from bare wood on which the adhesive resin is situated; and measuring and analyzing the high contrast image, using the image analysis software with resin analysis macros, to provide an output showing at least a percent resin coverage/grade of the wood sample.